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LS3 Carbed build

General engine tech -- Drag Racing to Circle Track

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gmrocket
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Re: LS3 Carbed build

Post by gmrocket » Tue Feb 04, 2020 1:03 pm

CGT wrote:
Tue Feb 04, 2020 11:06 am
Screenshot (44).png




This what the 4-1's looked like comparing corrected horsepower: From the left Pull 56 is Tri-y's with cam 2 backed up to 111° ICL(which hurt power), next pull over pull 57 is a backup pull to pull 56. Pull 58 is the switch to 4-1 header, pull 59 is a backup to pull 58.
I need some new eyes...blurry 🤓

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Re: LS3 Carbed build

Post by steve cowan » Tue Feb 04, 2020 1:19 pm

gmrocket wrote:
Tue Feb 04, 2020 1:03 pm
CGT wrote:
Tue Feb 04, 2020 11:06 am
Screenshot (44).png




This what the 4-1's looked like comparing corrected horsepower: From the left Pull 56 is Tri-y's with cam 2 backed up to 111° ICL(which hurt power), next pull over pull 57 is a backup pull to pull 56. Pull 58 is the switch to 4-1 header, pull 59 is a backup to pull 58.
I need some new eyes...blurry 🤓
if you click on photo,then right click and open in new window it comes up fine
steve c

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Re: LS3 Carbed build

Post by gmrocket » Tue Feb 04, 2020 1:27 pm

steve cowan wrote:
Tue Feb 04, 2020 1:19 pm
gmrocket wrote:
Tue Feb 04, 2020 1:03 pm
CGT wrote:
Tue Feb 04, 2020 11:06 am
Screenshot (44).png




This what the 4-1's looked like comparing corrected horsepower: From the left Pull 56 is Tri-y's with cam 2 backed up to 111° ICL(which hurt power), next pull over pull 57 is a backup pull to pull 56. Pull 58 is the switch to 4-1 header, pull 59 is a backup to pull 58.
I need some new eyes...blurry 🤓
if you click on photo,then right click and open in new window it comes up fine
Tried that...it's my phone, laptop it's good. Thanks

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Re: LS3 Carbed build

Post by CGT » Tue Feb 04, 2020 2:28 pm

steve316 wrote:
Tue Feb 04, 2020 9:44 am
Chad a merge collector with 2.5 choke will want less jet. most of the time make the same power but go down the track quicker. Not sure of reason, just what I have experienced.
This post prompted me to look at my AFR's for the 4-1 pulls, like I mentioned it was the last 2 pulls and I was ready to be done. So, if I would have corrected the AFR'S, the 4-1's would have been closer im sure...or maybe even better somewhere. But could also be difference in 02 sensor location between headers.

Screenshot (46).png
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Re: LS3 Carbed build

Post by steve cowan » Wed Feb 05, 2020 1:35 am

Chad,
Like your new signature :D
Looking at afr on your dyno sheet
Q16 has a stoich of 13.4
Your afr was 12.7average there abouts which is 5% richer
What direction would you go?? As far as tuning 4-1 headers
Seemed as you were taking fuel away it was still making good progress.
I know next to nothing on headers and would be a can of worms chasing it, so many variables.
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Re: LS3 Carbed build

Post by CGT » Wed Feb 05, 2020 9:25 am

Screenshot (48).png




I just noticed I had pull 59 on there twice on the previous post. So this is 2 pulls with tri y's and 2 with 4-1. My point was that it appears the 4-1's fattened up the AFR's, and if that's true...I would only know by jetting for best power afterwards... the 4-1's could be closer than I think...this engine likes to run lean for sure.

It could also be sensor location between headers, or residue on the sensor...because it appears to progressively richen up on these 4 pulls a little each progressive pull, and these 4 pulls were consecutive.

These pulls are not Q16..(only 4 of those made), they are VP Late Model Plus non-oxy.
steve cowan wrote:
Wed Feb 05, 2020 1:35 am
What direction would you go?? As far as tuning 4-1 headers
If I had to take a stab at it, I'd wanna see something on there with shorter primary's, better angle coming off the head like Randy mentioned, with a smaller merge collector. But my track record with header predictions is not good 8)


I was just looking at AFR's through all the pulls, Q and LMP fuel, it appears the AFR's are a bit erratic through the whole session, 02 sensor could be coming to the end of its life cycle. :lol: . I didn't touch a jet in my 1050 this whole session, it was as it was from the previous dyno session other than upping it 4 sizes for the 4 Q pulls then putting it back. To make the header test more accurate, both sets of headers would have needed to have the carb tuned for best power actually..irregardless of 02 readings.
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Re: LS3 Carbed build

Post by randy331 » Thu Feb 06, 2020 12:38 am

How about pulling some spring out of it for a few pulls ?
Maybe not to 8200 rpm. LOL

Be interesting to see if less spring made any difference in the lower part of the rpm range it was pulled in.

I'd want less seat and same rate, or same seat and less rate.
That may tell you more than just less spring on both seat and rate.
Kinda wonder what a hyd lifter really does on the running engine??

That'd be interesting to see if anything showed up as far as power difference.

Randy

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Re: LS3 Carbed build

Post by steve cowan » Thu Feb 06, 2020 1:23 am

randy331 wrote:
Thu Feb 06, 2020 12:38 am
How about pulling some spring out of it for a few pulls ?
Maybe not to 8200 rpm. LOL

Be interesting to see if less spring made any difference in the lower part of the rpm range it was pulled in.

I'd want less seat and same rate, or same seat and less rate.
That may tell you more than just less spring on both seat and rate.
Kinda wonder what a hyd lifter really does on the running engine??

That'd be interesting to see if anything showed up as far as power difference.

Randy
Randy,
Are you thinking that there might be more area available below peak torque if lifter is not collapsing some??
I thought it interesting how Chad mentioned shorter primary pipe and smaller choke merge colletor, I think it would require cam timing sweeps with header change.
I mentioned earlier about overscavanging at high rpms, does the steeper valve seats negate that at higher rpm or is it more valve timing /INOP EXCL or even headers, possibly combination of all??
What is the rpm cutoff for this engine as in OEM parts are being pushed to the limits surly :shock:
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Re: LS3 Carbed build

Post by gmrocket » Thu Feb 06, 2020 5:58 am

CGT wrote:
Tue Feb 04, 2020 2:28 pm
steve316 wrote:
Tue Feb 04, 2020 9:44 am
Chad a merge collector with 2.5 choke will want less jet. most of the time make the same power but go down the track quicker. Not sure of reason, just what I have experienced.
This post prompted me to look at my AFR's for the 4-1 pulls, like I mentioned it was the last 2 pulls and I was ready to be done. So, if I would have corrected the AFR'S, the 4-1's would have been closer im sure...or maybe even better somewhere. But could also be difference in 02 sensor location between headers.


Screenshot (46).png
is the dyno not capable of doing 8 O2 reads? if not, ive got around that by moving the leads four times to get my 8 individual afr's. we just made sure the 6 unused ones were powered so they didn't get fouled. you can get your 8 done in a few minutes. better than having to move the two into the next set of pipes and plugging the ones just done....the operator don't mind, its your time and money :lol:

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Re: LS3 Carbed build

Post by randy331 » Thu Feb 06, 2020 9:50 am

steve cowan wrote:
Thu Feb 06, 2020 1:23 am
Randy,
Are you thinking that there might be more area available below peak torque if lifter is not collapsing some??
Well, you never really know what that hyd lifter does. How much collapse etc.
Less spring may increase actual time/area/lift on the running engine up to the limits of valve train control.

I guess I could try it on the lsx 454 when I dyno it?? It will be a lower rpm engine but same type of lift.
I have higher seat/rate springs for it. I could put the stock ones back on for a few pulls.

Randy

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Re: LS3 Carbed build

Post by CGT » Thu Feb 06, 2020 10:19 am

gmrocket wrote:
Thu Feb 06, 2020 5:58 am
....the operator don't mind, its your time and money
That's for sure, Joe just always says "do whatever you wanna do, come get me when your ready to make a lap" lol
randy331 wrote:
Thu Feb 06, 2020 9:50 am
I guess I could try it on the lsx 454 when I dyno it?? It will be a lower rpm engine but same type of lift.
I have higher seat/rate springs for it. I could put the stock ones back on for a few pulls.
That could be interesting. I could also grab that cam with the LSL intake lobes to try if you want.
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Re: LS3 Carbed build

Post by steve cowan » Wed Feb 12, 2020 11:15 pm

Chad,
I seen on the other thread you talking about piston speed,
I put the some inputs into pipemax and I understand that I don't have all the correct parameters but at 8400 rpm it shows piston speed Just over 5000 fpm
Does this sound close and if so what would be the limit for OEM rods apart from one breaking :shock:
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Re: LS3 Carbed build

Post by CGT » Thu Feb 13, 2020 9:09 am

steve cowan wrote:
Wed Feb 12, 2020 11:15 pm
I seen on the other thread you talking about piston speed,
I put the some inputs into pipemax and I understand that I don't have all the correct parameters but at 8400 rpm it shows piston speed Just over 5000 fpm
Yeah, that's what I get also.
steve cowan wrote:
Wed Feb 12, 2020 11:15 pm
Does this sound close and if so what would be the limit for OEM rods apart from one breaking
Im sure its well beyond OE design limits, but not crazy high at all if it had better parts. I am glad I decided to at least put some ARP 2000 bolts in the rods at this point. But I don't have enough data or experience with it other than referencing some "known" engines, and classes and what their mean speeds are.

The reference to it in the other thread had to do with my cam pick for his 454 LSX..which was about 10° longer than his pick. He pointed out that, pushing peak hp rpm up or power beyond peak on the 454 would put it at and above 5000fpm zone real easy. At 7000ish it hits that on the 454.

I think Randy got real familiar with piston speeds playing around with pulling trucks. :D
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Re: LS3 Carbed build

Post by randy331 » Thu Feb 13, 2020 8:11 pm

CGT wrote:
Thu Feb 13, 2020 9:09 am

I think Randy got real familiar with piston speeds playing around with pulling trucks. :D
Yes, the piston speeds get high on a lot of pulling trucks for sure.

The 421 has been well over 6000 fpm mean piston speed a lot.
Just wish we could get the sled speed up to the same as the piston speeds. LOL

Steve, use stroke x rpm / 6 to get mean piston speed for an engine.

Example,... the 421 has a 3.875 stroke so 3.875 x 9500 rpm = 36,812.5---- 36812.5 / 6 = 6135 fpm
See, we never get the sleds up to that speed. :D
But,... don't think I'd want to be driving the pulling truck if that happened. LOL

Got a Big Block Chevy pulling truck engine in the shop now with just a 3.5" stroke. Piston speed on it won't get out of hand as easy.

Randy

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Re: LS3 Carbed build

Post by MadBill » Thu Feb 13, 2020 9:15 pm

randy331 wrote:
Thu Feb 06, 2020 9:50 am
steve cowan wrote:
Thu Feb 06, 2020 1:23 am
Randy,
Are you thinking that there might be more area available below peak torque if lifter is not collapsing some??
Well, you never really know what that hyd lifter does. How much collapse etc.
Less spring may increase actual time/area/lift on the running engine up to the limits of valve train control.

I guess I could try it on the lsx 454 when I dyno it?? It will be a lower rpm engine but same type of lift.
I have higher seat/rate springs for it. I could put the stock ones back on for a few pulls.

Randy
How about just cranking the hot preload down to a few thous for a quick pull? True, the rocker/pushrod geometry might be sub-optimal but it should be good enough to highlight any lifter collapse effects and if you keep the revs in check there would be no chance of the potentially huge pump-up causing valve/piston contact..
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